Review Reports

Round 1

Reviewer 1 Report

In this article, the authors study the effect of varying the sintering temperature and the binder concentration on the synthesis of CaO.SiO₂ catalysts, manufactured from brick burning ash, with the intention that these catalysts be used in the biodiesel manufacturing process.

In general terms, I consider that the study is too partial, since it covers only some structural aspects of the catalysts, but no aspect that allows evaluating their performance in the reactions for which they were designed. Therefore, it is not possible to know if these catalysts will be useful or not.

On the other hand, some expressions must be corrected, for example:

-lines 59-61: if the reaction conditions are reported in range, the conversion value must also be a range, it can never be an exact value.

-lines 97-99: firstly, the text says that limestone is CaCO₃, and in the next line it says that CaCO3 is the main component of limestone. One of the two definitions is wrong.

-line 108: in the expression “The binding material used in the manufacture of this catalyst is tapioca flour”, are you referring to all catalysts? Or in Masri's studio? Or those of this particular study?.

 

-line 376: according to the text, this figure corresponds to different temperatures, not % binder.

-line 392: the expression “When the temperature exceeds 1000°C” is wrong, given that at no time in the study did the temperature exceed 1000°C.

 

-line 449: the expression “%Si and ca content fluctuates”, must be corrected.

 

In Section 2.1.5, the value “variable 5” seems to behave completely differently from the others. It would be interesting if the authors explain what is happening, since the %binder does not seem to have a significant effect on the other properties studied.

Regarding English, I think that many terms and expressions throughout the manuscript are not the most appropriate, for example:

-lines 258-259: “Violence has a rela tionship with density, where if the density is high, the tendency of the value of violence will rise”. The word violence does not seem to be the most appropriate.

Author Response

Thank you. 

We apologize for the delay in replying to the review article. 

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript ID: catalysts-2371516

Title: Effect of Temperature and Tapioca Flour Concentration on Manufacture of CaO.SiO₂ Heterogeneous Catalyst Pellets Made from Brick Burning Ash for Biodiesel Making.

This manuscript presents an experimental work focused on catalyst development. The effect of binder (tapioca flour) concentration and sintering temperature are studied on manufacture of CaO.SiO₂ catalysts. The field of research is relevant. This manuscript is suitable for publishing after minor revisions.

Comments:

1.- The authors should provide more details about brick burning ash. The source of bricks and the effect of burning the bricks to obtain ash. Please, explain this previous step.

2.- In line 135, the sentence: “Density is a metric that indicates pore size or the number of pores.” should be better explained. The characterization of samples by nitrogen adsorption should be useful to determine pore size and pore volume, moreover surface area.

3.- In section 2.1 Effect of Binder Composition on Characteristics of CaO.SiO₂ Pellet Catalyst, the authors should specify all the preparation steps of the pellet catalyst: particle size, compaction and sintering temperature.

4.- PSA analysis, sections 2.1.3 and 2.2.3, should be revised. For example, in section 2.1.3 the sentences: “A good uniformity range is at nanosize, which is between 0.6 nm to 7 m. The results of the CaO.SiO₂ catalyst test showed that the catalyst obtained was microporous in the range of 120 nm – 100 m.” According to Fig. 5 the particle size is between 0.06 mm and 0.08 mm. A microporous material has a pore size smaller than 2 nm. Please, explain.

5.- In section 2.2 Effect of Sintering Temperature on Characteristics of CaO.SiO₂ Pellet Catalyst, the authors should provide more details about the preparation steps previous to sintering, such as binder %, data of compacting and particle size, among others.

6.- Revise typographical errors through the whole manuscript. There are a lot of errors in the text.

For example:

-        The figure caption of Figure 14

-        Sentence in lines 37-40.

-        Lines 191-192

-        Line 249

-        Line 309

Author Response

Here with I sen, our comments for the results review

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The minor revisions raised have been resolved satisfactorily, facilitating the reading of the manuscript and resolving.

However, from my point of view, the two substantive issues I raised (Point 1 and 8) were explained but not resolved, so as far as those two issues are concerned, the manuscript has not been improved.